A typical monolithic semiconductor device, such as transistors and integrated circuits, usually includes a depletion region formed when an internal PN junction is reversed biased. Under high voltage conditions, the depletion region extends away from the junction a substantial distance, particularly in lightly doped regions.
In the event a depletion region is permitted to extend to the unpassivated edge of a die, the performance of the device is severely degraded. One conventional solution to the foregoing problem is to open a contact area in the oxide layer covering the die and form a separate metallization ring which extends around the active region of the device and maintains the edge of the device at a uniform potential equal to that of the back of the die. One disadvantage of this approach is that additional processing steps must be carried out to form the extra metallization ring. In addition, it is not usually convenient to connect the ring to the back of the die and as a consequence, the die edge is not maintained at an optimum uniform potential.
The present invention overcomes the above-noted limitations of conventional semiconductor devices. A metallization structure is formed which, while providing an ohmic contact with the body region of the device, requires no additional processing steps. In addition, the metallization structure is maintained at the same potential as the back of the die without the requirement of a separate connection. In addition, breakdown voltage measurement and related performance characteristics are substantially the same before and after the scribing and breaking of the wafer so that reliable device testing can be performed in wafer form, thereby reducing manufacturing costs. These and other advantages of the present invention will become apparent to those skilled in the art upon reading the following Best Mode For Carrying Out The Invention together with the drawings.